The present invention relates to vehicle ride control systems and more particularly to a control system for controlling vehicle ride in real-time.
A variety of vehicle ride control systems have been developed to provide real-time control over vehicle ride. For example, ride control systems have been developed to adjust in real-time the damping forces of a damper, such as a hydraulic shock, during both compression and rebound in response to road irregularities and other vehicle conditions. These adjustments are made as a function of a variety of factors, including a variety of sensed variables that are indicative of acceleration, deceleration, cornering, road impacts and other similar vehicle characteristics. One system designed to generate a constant compression and/or rebound force at a wheel is disclosed in PCT International Publication No. WO 96/05975, which is entitled Computer Optimized Adaptive Suspension System and Method Improvements and was published on Feb. 29, 1996. PCT International Application No. WO 96/05975 is incorporated herein by reference in its entirety. Since the development of the suspension system disclosed in WO 96/05975, a number of improvements in its control system and control methodology have been developed. A number of these improvements are disclosed in U.S. Pat. No. 6,502,837, which is entitled “Enhanced Computer Optimized Adaptive Suspension System And Method” and issued to Hamilton et al on Jan. 7, 2003. U.S. Pat. No. 6,502,837 is incorporated herein by reference in its entirety.
Although existing vehicle ride control suspension systems can provide marked improvement in handling, comfort and control of a vehicle, experience has revealed that the more effective conventional systems are excessively large and difficult to fit into the space available in existing vehicles. As a result, the commercial acceptance of ride control suspension systems has been somewhat limited. For example, in actual implementation, the ride control system of the references identified above includes a suspension control unit located at each wheel. Each suspension control unit includes a hydraulic damper with separate pressure regulators for the compression and rebound chambers, along with a fluid accumulator. Each suspension control unit also includes a separate computer controller and associated housing that is packaged with the mechanical and hydraulic components. Further, each suspension control unit includes an accumulator having an integrated LVDT that determines wheel position based essentially on the position of the piston within the accumulator. As a result of the expansion and contraction in oil volume that occurs with changes in temperature, the integrated wheel position sensor requires complicated algorithms to provide proper compensation for temperature-based changes in oil volume. In combination, the components of these prior systems are relatively bulky and rather difficult to fit into the packaging constraints of many conventional vehicle designs. Further, at least some of the components of these prior systems operate at a high level of complexity, thereby increasing cost and potentially reducing reliability. The systems are also relatively expensive to manufacture and assemble, thereby further reducing the commercial appeal of ride control suspension systems.
Accordingly, there is a long-felt and unmet need for an effective and reliable vehicle ride control suspension system that satisfies the packaging requirements of conventional vehicle designs and is economical to produce.